During Phase I research a new technology was discovered for monitoring affinity interactions. Using proprietary transducer material and chemical modification processes, analyte concentration-related affinity responses were detected. The resulting signal is easily amplified with off the shelf microchip components. As a result of the low cost and robust nature of the transducer material and microcircuitry, it is anticipated that low cost, highly durable biosensors can be developed. During Phase II, we will focus on developing a biosensor that can quantify theophylline levels in biological fluids. Theophylline was chosen as the analyte because; 1) the therapeutic levels are relatively high (i.e., mug/mL), 2) there are many suppliers of antitheophylline antibody, and 3) many people suffer from respiratory ailments and require theophylline. PROPOSED COMMERCIAL APPLICATION: Theophylline biosensors will be used to monitor blood levels of this drug in clinical laboratories, and point- of-care settings where post turn-around times are critical.